The invention relates to an improved audible signaling device. In environments where multiple warning devices are present, or where there is significant background noise, there is a need for unique audible warning sounds. One way to make a unique warning sound is to include multiple harmonic frequency components in addition to the fundamental frequency of the warning sound. See, for example, IEC 60601-1-8, “Medical Electrical Equipment—Part 1-8: General Requirements for Safety—Collateral Standard” General Requirements, Tests and Guidance for Alarm Systems in Medical Electrical Equipment and Medical Electrical Systems,” 1st edition, 2003, published by the International Electrotechnical Commission, 3 rue de Varembe, P.O. Box 131, CH-1211, Geneva 20, Switzerland. One advantage from embedding multiple frequencies in an audible sound is that it is easier for a person to locate the origin of the sound. If the background noise masks one or more of the frequencies that make up the sound, the other unmasked sound frequencies can still be heard.
There is also a need for low frequency audible warning sounds because the lower frequency is an alternative to commonly used warning sound frequencies, and because the ability to hear higher frequency sounds generally decreases as a person ages. Currently available technology used to produce a loud, low frequency warning sound with multiple relatively equal frequency components requires the use of a sophisticated controller, expensive power electronics to amplify the electrical drive signal, and a large wattage speaker.
This new signaling device enables the generation of a loud, low frequency warning sound with relatively equal multiple frequency components without necessarily the need for a sophisticated controller, large power electronics, or a large wattage speaker.